📖 Instructions

1. First things first, let's get those green beans ready. Fill a large pot with lightly salted water and bring it to a rolling boil. While that’s heating up, trim the ends off your fresh green beans. Once the water boils, carefully add the trimmed green beans. You're going to blanch them for about 4-6 minutes. We're looking for 'tender-crisp' here—they should be bright green and still have a slight bite, not mushy! Immediately drain the beans and plunge them into a large bowl of ice water to stop the cooking process. This helps them keep that vibrant color and crisp texture. After a few minutes, drain them again thoroughly and set aside.
2. Now for the heart of our casserole: the rich gravy! Grab a large oven-safe skillet or a Dutch oven. Melt 4 tablespoons of butter over medium heat. Add your sliced cremini mushrooms and chopped yellow onion. Sauté these beauties for about 8-10 minutes, or until the onions are soft and translucent, and the mushrooms have released their liquid and browned nicely. This browning is key for depth of flavor, don't rush it! Stir frequently.
3. Once your veggies are softened and lightly browned, sprinkle the 1/4 cup of all-purpose flour over them. Stir continuously for 1-2 minutes, letting the flour cook into a roux with the butter and vegetable juices. It'll thicken up and look a little paste-like. This step is crucial for thickening our gravy and getting rid of that raw flour taste.
4. Slowly, and I mean *slowly*, whisk in the 2 cups of low-sodium chicken broth. Do it gradually to avoid lumps. As you add the broth, keep whisking until the mixture is smooth and begins to thicken. Next, pour in the 1 cup of milk and 1/2 cup of heavy cream, whisking them in well. Bring the mixture to a gentle simmer, still whisking occasionally. It should become thick and luxurious, coating the back of a spoon.
5. Time to season our masterpiece! Stir in the 1 teaspoon of garlic powder, 1 teaspoon of onion powder, 1/2 teaspoon of black pepper, and 1 teaspoon of salt (remember, you can always add more salt later, but you can't take it out!). Add the 1 tablespoon of fresh chopped thyme. Let the gravy simmer gently for another 5 minutes, allowing all those flavors to meld together. Taste it! Adjust seasonings if needed. Is it savory enough? Does it need a tiny pinch more salt? Your call!
6. Preheat your oven to 375°F (190°C). If you’re not using an oven-safe skillet, transfer the gravy to a 9x13-inch baking dish. Gently fold the blanched green beans into the rich gravy, making sure every bean is beautifully coated. Give it a good stir to combine everything evenly. Oh, this is gonna be good!
7. Bake the casserole, uncovered, for 20 minutes. You’re looking for the gravy to be bubbly and the casserole heated through. The beans should be perfectly tender. This baking time also helps the flavors deepen even further. Keep an eye on it—we don't want any burnt spots!
8. Remove the casserole from the oven. Now for the grand finale: sprinkle the entire 6 oz can of crispy fried onions generously over the top. You can use homemade ones too, if you're feeling extra ambitious! Return the casserole to the oven for another 5-10 minutes, or until those fried onions are golden brown and perfectly crispy. Be careful not to burn them; they can go from golden to charred pretty quickly.
9. Let it rest! I know, I know, it's hard to wait. But letting the casserole sit for about 5-10 minutes after it comes out of the oven allows the gravy to set up a bit more and prevents it from being too runny. This also ensures it's not scorching hot when you serve it. Serve warm and watch it disappear. Enjoy every comforting, delicious bite!